Ruby has a nifty little function called time_ago_in_words. You pass it an arbitrary number of seconds and it gives you back something friendly like “about 2 weeks ago”.
Today, I implemented a similar routine for .NET.
nuget.org/List/Packages/relativetime
To use it, just include the namespace, then call ToHumanTime() on a TimeSpan object.
If you want more of an idea of what it generates, take a look at the test suite.
Tatham Oddie 
That’s a great one, Tatham
Thanks a lot for the library and mention of the other service. Checking both…
I had the same problem early 2010, and used another similar service, http://www.purl.org
It gave me URLs like:
http://purl.org/net/spiurl/meligy
But was always feeling a bit worried about using a random free service like this. The good thing is I never caught it falling, but you never know what’s coming…